Heat exchanger

ABSTRACT

A heat exchanger has a flat tube and a header in communication with the flat tube. The flat tube has a flat passage part and a groove part. The flat passage part defines a fluid passage therein. The groove part extends along the flat passage part. An end of the groove part is recessed from an end of the flat passage part in a longitudinal direction of the flat tube. The header has a tube insertion hole having a shape corresponding to an outline of the flat passage part. The end of the flat passage part is received in and fixed to the tube insertion hole of the header.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2006-98467 filed on Mar. 31, 2006, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a heat exchanger having flat tubes.

BACKGROUND OF THE INVENTION

In a heat exchanger, e.g., an evaporator, it is known to form draining grooves on flat tubes for smoothly draining condensation adhered to fins away from the heat exchanger. A heat exchanger having flat tubes with such draining grooves is for example disclosed in Japanese Unexamined Patent Publications No. 7-190661 and No. 10-197173.

In manufacturing such flat tubes with the draining grooves, it is generally required to reduce a materials cost. To meet this demand, the flat tubes are formed by extrusion as thin as possible such that the thickness at a position corresponding to the draining groove is close to the limit of the extrusion (e.g., 0.3 mm).

In a header of the heat exchanger, tube insertion holes for receiving ends of the flat tubes are formed such as by stamping in the shape corresponding to the outline of the flat tubes including the draining grooves. With the above decrease of the thickness of the tubes, it is necessary to reduce a dimension of the tube insertion holes. However, it is difficult to form the tube insertion holes to correspond to the reduced thickness of the flat tubes, particularly, at portions corresponding to the draining grooves, which are very thin as the limit of the extrusion. Otherwise, the thickness of the flat tubes may be increased to increase the thickness at the positions corresponding to the draining grooves so as to ease the forming of the tube insertion holes. However, this may result in an increase of the materials cost.

SUMMARY OF THE INVENTION

The present invention is made in view of the foregoing matter, and it is an object of the present invention to provide a heat exchanger in which a tube insertion hole is easily formed on a header.

According to an aspect of the present invention, a heat exchanger has a flat tube and a header in communication with the tube. The flat tube has a flat passage part defining a fluid passage therein through which a fluid flows and a groove part. The groove part has a plate shape having a thickness smaller than a thickness of the flat passage part. The groove part extends along the flat passage part and an end of the groove part is recessed from an end of the flat passage part by a predetermined distance in a longitudinal direction of the flat tube. The header has a tube insertion hole having a shape corresponding to an outline of the flat passage part, and the end of the flat passage part is received in the tube insertion hole.

The end of the groove part is recessed from the end of the flat passage part and is not received in the header. Therefore, it is not necessary to form the tube insertion hole in a shape corresponding to a whole outline of the flat tube. That is, the tube insertion hole has the shape corresponding to the outline of the flat passage part. Accordingly, it is easy to form the tube insertion hole on the header.

For example, the tube has a plurality of flat passage parts. The flat passage parts are aligned in a direction in which a width of the flat passage part is measured. The groove part is disposed between and connect the adjacent flat passage parts. Also in this case, the end of the groove part is recessed from the end of the adjacent flat passage parts in the longitudinal direction of the flat tube. Thus, only the ends of the flat passage parts are received in the tube insertion holes of the header. The tube insertion holes merely have the shape corresponding to the outline of the flat passage part. Therefore, the tube insertion holes are easily formed.

Alternatively, the tube has two groove parts on opposite sides of the flat passage part. The groove parts have plate shape projecting from the sides of the flat passage part in the direction in which the width of the flat passage part is measured. Also in this case, the ends of the groove parts are recessed from the end of the flat passage part so that only end of the flat passage part is received in the tube insertion hole. Therefore, the tube insertion hole merely has the shape corresponding to the outline of the flat passage part. Thus, the tube insertion hole is easily formed. For example, the tubes may be arranged in the direction in which the width of the flat passage part is measured such that the groove parts of adjacent tubes do not overlap with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:

FIG. 1A is a schematic perspective view of a heat exchanger according to a first embodiment of the present invention;

FIG. 1B is an enlarged view of a part of the heat exchanger denoted by a bashed line 1B in FIG. 1A;

FIG. 2A is a plan view of an end of a flat tube of the heat exchanger when viewed along an arrow A1 in FIG. 1B;

FIG. 2B is a schematic cross-sectional view of the flat tube taken along a line IIB-IIB in FIG. 2A;

FIG. 2C is a partial plan view of a header plate of a header of the heat exchanger according to the first embodiment;

FIG. 2D is a cross-sectional view of the header according to the first embodiment;

FIG. 3 is an explanatory view for showing insertion of the flat tube into the header according to the first embodiment;

FIG. 4 is a cross-sectional view of the header in which the end of the flat tube is coupled according to the first embodiment;

FIG. 5A is a plan view of an end of a flat tube of a heat exchanger according to a second embodiment of the present invention;

FIG. 5B is a schematic cross-sectional view of the flat tube taken along a line VB-VB in FIG. 5A;

FIG. 5C is a partial plan view of a header plate of a header of the heat exchanger according to the second embodiment;

FIG. 5D is a cross-sectional view of the header according to the second embodiment;

FIG. 6A is a plan view of an end of a flat tube of a heat exchanger according to a third embodiment of the present invention;

FIG. 6B is a schematic cross-sectional view of the flat tube taken along a line VIB-VIB in FIG. 6A;

FIG. 6C is a partial plan view of a header plate of a header of the heat exchanger according to the third embodiment; and

FIG. 6D is a cross-sectional view of the header according to the third embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS First Embodiment

A first embodiment of the present invention will now be described with reference to FIGS. 1A through 4. A heat exchanger 1 shown in FIG. 1 is for example an evaporator of a refrigerating cycle and is generally located outside of a compartment/room. The heat exchanger 1 has flat tubes 2, corrugated fins 3 and headers 4. In FIG. 1, the flat tubes 2 and the corrugated fins 3 are simply illustrated for convenience of illustration.

In the figures, an arrow D1 denotes a longitudinal direction of the flat tubes 2, an arrow D2 denotes a direction perpendicular to the longitudinal direction D1 and in which a width of the flat tube 2 (flat passage part) is measured. Also, an arrow D3 denotes a direction in which a thickness of the flat tube 2 (flat passage part) is measured. In this embodiment, the direction D3 also corresponds to a longitudinal direction of the header 4 of the heat exchanger 1. The direction D3 is perpendicular to the directions D1, D2. Hereafter, the direction D1 is referred to as a tube longitudinal direction, the direction D2 is referred to as a tube transverse direction, and the direction D3 is referred to as a header longitudinal direction.

The tubes 2 are arranged parallel to each other such that flat surfaces of the adjacent tubes 2 are opposed to each other in the header longitudinal direction D3. The corrugated fins 3 are arranged between the tubes 2 and thermally connected to the flat surfaces of the tubes 2.

The headers 4 are disposed at longitudinal ends of the stack of tubes 2 and corrugated fins 3. Longitudinal ends of the tubes 2 are coupled to the headers 4. The headers 4 are provided with a refrigerant inlet port and a refrigerant outlet port, respectively. The heat exchanger 1 further has end plates 5 at ends of the stack of tubes 2 and corrugated fins 3 for protecting the corrugated fins 3 arranged on outermost layers of the stack of tubes 2 and corrugated fins 3.

As shown in FIGS. 1B, 2A, 2B, each of flat tubes 2 has flat passage parts 6 a, 6 b, 6 c aligned in the tube transverse direction D2. In the illustrated example, the tube 2 has three flat passage parts. Each of the flat passage parts 6 a, 6 b, 6 c generally has a flat shape. As shown in FIG. 2B, in a cross-section of each flat passage part 6 a, 6 b, 6 c defined in a direction perpendicular to the tube longitudinal direction D1, a dimension (thickness) in the header longitudinal direction D3 is smaller than a dimension (width) in the tube transverse direction D2 (left and right direction in FIG. 2B).

Further, each of the flat passage parts 6 a, 6 b, 6 c has a plurality of refrigerant passages 7 therein. The refrigerant passages 7 are aligned in the tube transverse direction D2. The refrigerant passages 7 extend in the tube longitudinal direction D1 from an end to the other end and allows communication between the upper and lower headers 4.

Also, each tube 2 has a first groove plate 8 a and a second groove plate 8 b as groove parts. The first flat passage part 6 a and the second flat passage part 6 b are connected through the first groove plate 8 a. Likewise, the second flat passage part 6 b and the third flat passage part 6 c are connected through the second groove plate 8 b.

The first and second groove plates 8 a, 8 b have a thin plate shape. Thus, a thickness of the first and second groove plates 8 a, 8 b is smaller than the dimension (thickness) of the first to third flat passage parts 6 a, 6 b, 6 c in the header longitudinal direction D3. In the stack of tubes 2 and corrugated fins 3, outer surfaces of the flat passage parts 6 a, 6 b, 6 c are joined to the corrugated fins 3, and clearances are maintained between the corrugated fins 3 and the first and second groove plates 8 a, 8 b.

The first and second groove plates 8 a, 8 b extend in the tube longitudinal direction D1. Thus, the clearances provided between the first and second groove plates 8 a, 8 b and the corrugated fins 3 serve as draining groves for draining condensation in the tube longitudinal direction D1.

As shown in FIG. 2A, ends 11 of the first and second groove plates 8 a, 8 b are recessed from ends 10 of the first to third flat passage parts 6 a, 6 b, 6 c in the tube longitudinal direction D1 such that notches 9 are formed at the longitudinal end of the tube 2. For example, in FIG. 2A, a length of the first and second groove plates 8 a, 8 b from a line IIB-IIB (reference position) to the ends 11 thereof is smaller than a length of the flat passage parts 6 a, 6 b, 6 c from the line IIB-IIB to the ends 10 thereof.

Each of the headers 4 is constructed of a header plate 12 and a header tank 13. The header plate 12 and the header tank 13 have length in the header longitudinal direction D3. The headers 4 are arranged such that the header plate 12 of one header 4 is opposed to the header plate 12 of the other header 4 relative to the tube longitudinal direction D1.

As shown in FIG. 2C, each header plate 12 is formed with a plurality of first to third tube insertion holes 16 a, 16 b, 16 c on its wall 15. Each of the first to third tube insertion holes 16 a, 16 b, 16 c has a shape corresponding to the outline of the cross-sectional shape of each of the flat passages parts 6 a, 6 b, 6 c. The first to third tube insertion holes 16 a, 16 b, 16 c are aligned in the tube transverse direction D2. Each tube 2 is coupled to the header 4 such that the ends 10 of the flat passage parts 6 a, 6 b, 6 c are received in the tube insertion holes 16 a, 16 b, 16 c.

In the illustrated example, each of the flat passage parts 6 a, 6 b, 6 c has a hexagonal outline in the cross-section thereof. Thus, each of the tube insertion holes 16 a, 16 b, 16 c forms a hexagonal opening.

For example, the tube 2 is formed by extrusion as thin as possible. In this case, the thickness of the flat passage parts 6 a, 6 b, 6 c is about 1 mm in the header longitudinal direction D3, for example. Also, the thickness of the first and second groove plates 8 a, 8 b in the header longitudinal direction D3 is approximately 0.3 mm, which is generally a minimum thickness (limit) of the extrusion.

In a case that groove plates are ended at the same position as the ends of flat passage parts i.e., the ends of the groove plates are aligned with the ends of the passage parts, it is necessary to form an opening as the tube insertion hole in the shape corresponding to an entire outline of the cross-section of the tube including the groove plates. In this case, since the groove plates are very thin as the limit of extrusion, it is necessary to form the opening with a very small dimension as a limit of stamping, particularly, at positions corresponding to the groove plates.

In the first embodiment, on the other hand, the ends 11 of the first and second groove plates 8 a, 8 b are not inserted to the tube insertion holes 16 a, 16 b, 16 c of the header plate 12. Therefore, it is not necessary to form openings with such very small dimension as the limit of stamping for receiving the ends 11 of the first and second groove plates 8 a, 8 b. The tube insertion holes 16 a, 16 b, 16 c only for receiving the ends 10 of the tubes 2, which have the relatively simple outline, are formed on the wall 15 of the header plate 12. Since the dimension of the tube insertion holes 16 a, 16 b, 16 c are relatively large, the tube insertion holes 16 a, 16 b, 16 c are easily formed.

Even if the tube 2 is extruded as thin as possible close to the limit of extrusion, the tube insertion holes 16 a, 16 b, 16 c are easily formed by stamping. With this, the amount of material for the tubes 2 is reduced. As such, a materials costs of the tubes 2 reduces.

As shown in FIG. 2D, the header plate 12 and the header tank 13 are brazed at longitudinal sides thereof (right and left ends in FIG. 2D), thereby to provide a tank space 17 between them for allowing the refrigerant to flow.

The tube 2 is coupled to the header 4, as shown in FIG. 3. Specifically, the ends 10 of the flat passage parts 6 a, 6 b, 6 c are inserted into the tube insertion holes 16 a, 16 b, 16 c in the tube longitudinal direction D1. FIG. 4 shows a coupled condition of the tube 2 and the header 4.

As shown in FIG. 4, when the tube 2 is coupled to the header 4, the ends 11 of the first and second groove plates 8 a, 8 b are held on the wall 15 of the header plate 12. Thus, the ends 10 of the flat passage parts 6 a, 6 b, 6 c are held at a predetermined position between the header plate 12 and the header tank 13 with the tank space 17. Namely, the ends 10 of the flat passage parts 6 a, 6 b, 6 c are inserted by the predetermined length (inserting margin) D within the tank space 17, and a predetermined clearance 19 is maintained between the ends 10 of the flat passage parts 6 a, 6 b, 6 c and an inner surface 18 of the header tank 13.

In this condition, the outer peripheries of the flat passage parts 6 a, 6 b, 6 c and the perimeters of the tube insertion holes 16 a, 16 b, 16 c are brazed to have fluid-tightness. Accordingly, the tubes 2 and the headers 4 are joined.

Since the clearance 19 is maintained between the ends 10 of the flat passage parts 6 a, 6 b, 6 c and the inner surface 18 of the header tank 13, the flow of the refrigerant in the refrigerant passages 7 and the tank space 17 is facilitated. Here, the dimension of the notches 9 in the tube longitudinal direction D1 can be determined in accordance with the inserting margin D and the dimension of the clearance 19, which is required for allowing the refrigerant to smoothly flow in the tank space 17.

The ends 11 of the first and second groove plates 8 a, 8 b are configured to be held on the wall 15 of the header plate 12. Therefore, it is not always necessary to make the ends 11 of the first and second groove plates 8 a, 8 b fully contact the wall 15 of the header plate 12. Namely, it is not necessary to process the notches 9 precisely. The notches 9 are easily formed.

Also, since the tube insertion holes 16 a to 16 c have the relatively simple shape, the quality of brazing between the ends 10 of the flat passage parts 16 a to 16 c and the header plate 12 improves.

Second Embodiment

A second embodiment will be described with reference to FIGS. 5A to 5D. Here, the shape of draining grooves of the flat tubes 2 is different from that of the flat tube 2 of the first embodiment. Hereafter, like parts are denoted by like reference numerals and a description thereof will not be repeated.

As shown in FIGS. 5A and 5B, the flat tube 2 has first to third flat passage parts 21 a, 21 b, 21 c aligned in the tube transverse direction D2. Also, the flat tube 2 has a first groove part 22 between the first and second flat passage parts 21 a, 21 b and a second groove part 23 between the second and third flat passage parts 21 b, 21 c. The first groove part 22 and the second groove part 23 have a plate shape but includes a bend.

Specifically, the first groove part 22 includes a first plate portion 22 a, a second plate portion 22 c and a bend portion 22 b between the first and second plate portions 22 a, 22 c. The bend portion 22 b is located at a substantially middle position of the first groove part 22 in the tube transverse direction D2. The first plate portion 22 a and the second plate portion 22 c are staggered in the header longitudinal direction D3 by the bend portion 22 b.

For example, the first plate portion 22 a connects to a first surface of the first flat passage part 21 a (lower surface in FIG. 2B), and the second plate portion 22 c connects to a second surface of the second flat passage part 21 b (upper surface in FIG. 2B). The bend portion 22 b connects the first and second plate portions 22 a, 22 c.

Likewise, the second groove part 23 includes a first plate portion 23 a, a second plate portion 23 c and a bend portion 23 b between the first and second plate portions 23 a, 23 c. The bend portion 23 b is located at a substantially middle position of the second groove part 23 in the tube transverse direction D2. The first plate portion 23 a and the second plate portion 23 c are staggered in the header longitudinal direction D3 by the bend portion 23 b.

For example, the first plate portion 23 a connected to a first surface of the second flat passage part 21 b (lower surface in FIG. 2B), and the second plate portion 23 c connects to a second surface of the third flat passage part 21 c (upper surface in FIG. 2B). The bend portion 23 b connects the first and second plate portions 23 a, 23 c.

Although not illustrated in FIGS. 5A to 5B, corrugated fins are arranged between the adjacent tubes 2 that are stacked in the header longitudinal direction D3, similar to the first embodiment. The corrugated fins are thermally connected to the tubes 2. Each of the first and second groove parts 22, 23 provides two draining grooves. The dimension (depth) of the draining grooves substantially corresponds to a distance between the first surface and the second surface of the flat passage parts 21 a, 21 b, 21 c in the header longitudinal direction D3. Thus, the depth of the draining grooves is larger than that of the first embodiment. Accordingly, the condensation is more efficiently collected in the draining grooves and more efficiently drained, as compared to the first embodiment.

Similar to the first embodiment, ends 11 of the first and second groove parts 22, 23 are recessed from ends 10 of the flat passage parts 21 a, 21 b, 21 c in the tube longitudinal direction D1 to have the notches 9 at the longitudinal end of the tube 2. When the longitudinal end of the tube 2 is inserted to tube insertion holes 24 a, 24 b, 24 c of the header plate 12, the ends 11 of the first and second groove parts 22, 23 are held on the wall 15 of the header plate 12. Therefore, the inserting margin D of the ends 10 of the flat passage parts 21 a, 21 b, 21 c relative to the header 4 is determined.

FIG. 2C shows the shape of the tube insertion holes 24 a, 24 b, 24 c. Here, the tube insertion holes 24 a, 24 b, 24 c have the shape corresponding to the outline of the first to third flat passage parts 21 a, 21 b, 21 c, respectively. The first and third tube insertion holes 24 a, 24 c for receiving the end 10 of the first and third flat passage parts 21 a, 21 c have a pentagonal shape and the second tube insertion hole 24 b for receiving the ends 10 of the second flat passage part 21 b has a parallelogram shape.

Since the ends 11 of the first and second groove parts 22, 23 are recessed from the ends 10 of the first to third flat passage parts 21 a, 21 b, 21 c in the tube longitudinal direction D1, it is not necessary to form openings or holes on the header plate 12 for receiving the ends 11 of the first and second groove parts 22, 23. Namely, the tube insertion holes 24 a, 24 b, 24 c are formed only for receiving the ends 10 of the flat passage parts 21 a, 21 b, 21 c, which have the relatively simple shape. Therefore, the tube insertion holes 24 a, 24 b, 24 c are easily formed on the header plate 12.

Similar to the first embodiment, even if the tube 2 is extruded as thin as possible, the tube insertion holes 24 a, 24 b, 24 c are easily processed such as by stamping. Also, the amount of material of the tubes 2 reduces. As such, the materials cost of the tubes 2 reduces.

Third Embodiment

A third embodiment will be described with reference to FIGS. 6A to 6D. Here, the shape and arrangement of the flat tubes is different from that of the flat tubes of the first and second embodiments. Hereafter, like parts are denoted by like reference numerals and a description thereof will not be repeated.

As shown in FIGS. 6A and 6B, two flat tubes 20 a, 20 b are aligned in the tube transverse direction D2. The first flat tube 20 a has a first flat passage part 25 a having a hexagonal outline in a cross-section defined in the tube transverse direction D2. The first flat passage part 25 a defines refrigerant passages 7 therein. The first flat tube 20 a further has projections 26 a, 26 b as the groove parts. The projections 26 a, 26 b project from opposite sides of the first flat passage part 25 a in the tube transverse direction D2. The projections 26 a, 26 b are in the form of thin plate.

Likewise, the second flat tube 20 b has a second flat passage part 25 b having a hexagonal outline in a cross-section defined in the tube transverse direction D2. The second flat passage part 25 b defines refrigerant passages 7 therein. The second flat tube 20 b further has projections 27 a, 27 b as the groove parts. The projections 27 a, 27 b project from opposite sides of the second flat passage part 25 b in the tube transverse direction D2. The projections 27 a, 27 b are in the form of thin plate.

The projection 26 b of the first flat tube 20 a and the projection 27 a of the second flat tube 20 b are adjacent to each other in the tube transverse direction D2, but are not connected to each other.

The first flat tubes 20 a are arranged in line in the header longitudinal direction D3 and the second flat tubes 20 b are arranged in line in the header longitudinal direction D3. Further, the corrugated fins are arranged between the adjacent first and second flat tubes 20 a, 20 b and thermally connected to the first and second flat tubes 20 a, 20 b, similar to the first and second embodiments. Thus, clearances are maintained between the corrugated fins and the projections 26 a, 26 b, 27 a, 27 b. The clearances provide the draining grooves for draining the condensation.

Each corrugated fin has a width corresponding to a distance between an end of the projection 26 a and an end of the projection 27 b in the tube transverse direction D2. Thus, the sides of the corrugated fins are protected by the projections 26 a, 27 b.

As shown in FIG. 6A, the ends 11 of the projections 26 a, 26 b, 27 a, 27 b are recessed from the ends 10 of the flat passage parts 25 a, 25 b in the tube longitudinal direction D1. Thus, the notches 9 are provided at the longitudinal ends of the first and second flat tubes 20 a, 20 b.

As shown in FIGS. 6C and 6D, tube insertion holes 28 a, 28 b are formed on the header plate 12 for receiving the ends 10 of the flat passage parts 25 a, 25 b. For example, the tube insertion holes 28 a, 28 b are hexagonal openings to corresponds to the outline of the flat passage parts 25 a, 25 b.

When the longitudinal ends of the first and second flat tubes 20 a, 20 b are inserted into the tube insertion holes 28 a, 28 b of the header plate 12 in the tube longitudinal direction D1, the ends 11 of the projections 26 a, 26 b, 27 a, 27 b are held on the wall 15 of the header plate 12. As such, the inserting margin D of each flat passage parts 25 a, 25 b relative to the header plate 12 is determined.

Also in this case, it is not necessary to form openings for inserting the ends of the projections 26 a, 26 b, 27 a, 27 b, which serve as the draining grooves, on the header plate 12. Because the shape of the tube insertion holes 28 a, 28 b for receiving the ends 10 of the flat passage parts 25 a, 25 b are relatively simple, the tube insertion holes 28 a, 28 b are easily processed by such as stamping.

Even if the first and second tubes 20 a, 20 b are extruded as thin as possible, the tube insertion holes 28 a, 28 b are easily formed on the header plate 12 such as by stamping. Since the first and second tubes 20 a, 20 b are formed as thin as possible, the amount of material of the flat tubes 20 a, 20 b is reduced. As such, the materials cost of the tubes 20 a, 20 b reduces.

Other Embodiments

In the above embodiments, the wall 15 of the header plate 12 on which the tube insertion holes 16 a to 16 c, 24 a to 24 c, 28 a, 28 b are formed is flat. However, the wall 15 is not limited to the flat wall, but may have any shapes. For example, the wall 15 may have curved shape or M-letter shape in a cross-section defined in a direction perpendicular to the header longitudinal direction D3. In this case, the shape of the notches 9 may be changed to correspond to the shape of the wall 15 of the header plate 12, such as a curved shape or a M-letter shape.

In the above embodiments, the ends 11 of the groove plates 8 a, 8 b, 22, 23, 26 a, 26 b, 27 a, 27 b are held on the wall 15 of the header plate 12 so as to position the ends 10 of the flat passage parts 6 a, 6 b, 6 c, 21 a, 21 b, 25 a, 25 b within the tank space 17, when the ends 10 of the tubes 2, 20 a, 20 b are inserted into the tube insertion holes 16 a, 16 b, 16 c, 24 a, 24 b, 24 c, 28 a, 28 b. However, the ends 10 of the flat passage parts 6 a, 6 b, 6 c, 21 a, 21 b, 25 a, 25 b may be positioned by another way. For example, the flat tubes 2, 20 a, 20 b are positioned relative to the header 4 by using different jigs so that the ends 11 are not in contact with the wall 15 of the header plate 12 and clearances are maintained between the ends 11 and the wall 15 of the header plate 12.

In the above embodiments, the corrugated fins 3 are provided as outer fins of the heat exchanger 1. However, the outer fins may be another fins, such as plate fins.

Also, the number of flat passage parts 6 a, 6 b, 6 c, 21 a, 21 b, 21 c of one flat tube 2 is not limited to three. Further, the outlines of the flat passage parts 6 a, 6 b, 6 c, 21 a, 21 b, 21 c, 25 a, 25 b in the cross-section are not limited to the illustrated shape.

In the third embodiment, it is not always necessary that each tube 20 a, 20 b has two projections 26 a, 26 b, 27 a, 27 b. Instead, each tube 20 a, 20 b may have one projection. For example, the projections 26 a 27 b may be eliminated.

In the above embodiments, use of the heat exchanger is not limited to the evaporator of the refrigerating cycle. Also, a fluid flowing in the heat exchanger 1 is not limited to the refrigerant.

In the above embodiments, the heat exchanger 1 is constructed such that the fluid flows through the tubes 2 from one header 4 to the other header, i.e., in one direction. However, the structure of the heat exchanger 1 is not limited to the above. That is, the present invention may be employed to a heat exchanger having a fluid inlet and a fluid outlet on the same header and in which the fluid flows in a U-turn manner. Also, the present invention may be employed to a heat exchanger having a corrugated flat tube in which the fluid flows in a serpentine manner.

The example embodiments of the present invention are described above. However, the present invention is not limited to the above example embodiment, but may be implemented in other ways without departing from the spirit of the invention. 

1. A heat exchanger comprising: a flat tube; and a header in communication with the flat tube, wherein the flat tube has a flat passage part that defines a fluid passage therein through which a fluid flows and a groove part, the groove part has a plate shape having a thickness smaller than a thickness of the flat passage part, the groove part extends along the flat passage part and an end of the groove part is recessed from an end of the flat passage part by a predetermined distance in a longitudinal direction of the flat tube, the header has a tube insertion hole having a shape corresponding to an outline of the flat passage part, and the end of the flat passage part is received in the tube insertion hole.
 2. The heat exchanger according to claim 1, wherein the flat tube has a plurality of flat passage parts including the flat passage part, the plurality of flat passage parts is aligned in a direction in which a width of the flat passage part is measured, and the groove part is disposed between the adjacent flat passage parts and connects the adjacent flat passage parts.
 3. The heat exchanger according to claim 2, wherein the groove part has a flat plate shape.
 4. The heat exchanger according to claim 2, wherein the groove part is provided by a plate including a bend.
 5. The heat exchanger according to claim 4, wherein the plate includes a first plate portion and a second plate portion connected through the bend, the first plate portion and the second plate portion are staggered in a direction in which the thickness of the flat passage part is measured.
 6. The heat exchanger according to claim 1, wherein the groove part is a first groove part, and the flat tube further has a second groove part, wherein the first groove part and the second groove part project from opposite sides of the flat passage part in a direction in which a width of the flat passage part is measured.
 7. The heat exchanger according to claim 6, wherein the flat tube is one of a plurality of flat tubes, the plurality of flat tubes are aligned in the direction in which the width of the flat passage part is measured, the header has a plurality of tube insertion holes including the tube insertion hole, and each of the plurality of tube insertion holes has a shape corresponding to the outline of the flat passage part of each of the plurality of tubes.
 8. The heat exchanger according to claim 1, wherein the end of the flat passage part is brazed with a perimeter of the tube insertion hole.
 9. The heat exchanger according to claim 1, wherein the end of the flat passage part is located within the header and is spaced from an inner surface of the header by a predetermined distance, the inner surface opposed to the tube insertion hole in the longitudinal direction of the flat tube.
 10. The heat exchanger according to claim 1, wherein the end of the groove part is in contact with an outer surface of the header.
 11. The heat exchanger according to claim 1, wherein the header includes a header plate and a header tank, the header plate and the header tank are joined to each other and define a tank space therebetween, and the header plate has the tube insertion hole.
 12. The heat exchanger according to claim 1, wherein the flat tube is one of a plurality of flat tubes, the plurality of flat tubes is arranged in line in a direction in which the thickness of the flat passage part is measured, the heat exchanger further comprising: a plurality of fins disposed between the plurality of flat tubes.
 13. The heat exchanger according to claim 12, wherein the plurality of fins is one of a plurality of corrugated fins and a plurality of plate fins.
 14. The heat exchanger according to claim 12, wherein the plurality of fins are joined to outer surfaces of the flat passage parts of the plurality of flat tubes, and clearances are maintained between the groove part and the adjacent fins for providing draining grooves.
 15. The heat exchanger according to claim 1, wherein the flat tube is coupled to the header such that the longitudinal direction of the flat tube is perpendicular to a longitudinal direction of the header, and a direction in which the thickness of the flat passage part is measured is parallel to the longitudinal direction of the header. 